Ceramic thermal barrier coatings (TBC) are used to protect components for use at high temperatures from heat input. This is the case with turbine blades. For example, EP 2 845 924 A1 discloses using coating systems comprising a first ceramic layer of fully or partly stabilized zirconia and on it a layer that has a pyrochlore structure, such as gadolinium zirconate.
Because of greater thermal stresses in the case of turbine blades of a turbine, there are local temperature peaks in the pressure region of the turbine blade. This leads to greater consumption of the metallic protective layer or to spalling of the TBC. The use of cooling air holes would lead to the consumption of compressor air, and consequently to a reduction of efficiency.
Without countermeasures, the maximum running time of the turbine would be reduced.